Attachment Tech Annex

This document pretains to SAT-MOD-20141105-00121 for Modification on a Satellite Space Stations filing.

IBFS_SATMOD2014110500121_1067597

                                     ATTACHMENT A
                  Technical Information to Supplement Schedule S



A.1      SCOPE AND PURPOSE


The purpose of this Attachment is to provide the Commission with the technical characteristics of
the VIASAT-2 satellite, as modified. This attachment contains information that cannot be entered
into the Schedule S submission.


A.2      GENERAL DESCRIPTION


The VIASAT-2 satellite will provide a variety of Ka-band satellite services from the nominal 70º
W.L. orbital location, with an offset of 0.1° and the station-keeping box centered at 69.9° W.L.


The VIASAT-2 satellite’s beam coverage, both transmit and receive, consists of multiple spot
beams.    Figure A.2-1 shows the satellite’s service area in both the uplink and downlink
directions.


ViaSat has been granted U.S. market access for the 18.3-19.3 GHz and 19.7-20.2 GHz downlink
bands, and the 28.1-29.1 GHz and 29.5-30.0 GHz uplink bands.                This application for
modification does not seek market access for any additional frequency bands, and thus, ViaSat
provides technical information pertaining to the capabilities of the satellite for which market
access has already been granted.


The satellite network will provide service to small, fixed and temporary-fixed user antennas as
well as to very small antennas for mobile applications. In addition, larger gateway-type antennas
will be employed. The gateway-type antennas will have the capability of transmitting in any
channel within the 28.1-29.1 GHz and 29.5-30.0 GHz bands. Uplink transmissions from the
smaller user terminals will occur in the 28.35-29.1 GHz and 29.5-30.0 GHz bands.




                                                1


The satellite typically uses asymmetric forward (gateway-to-subscriber) and return (subscriber-
to-gateway) links. The network will use adaptive coding and modulation to combat rain fades.
That is, the modulation type, amount of coding and/or user data rate will be dynamically varied
to meet the link requirements during rain events (in addition to employing uplink power control).


Figure A.2-1. The VIASAT-2 satellite’s service area.

The map below illustrates the coverage area of the VIASAT-2 satellite. The coverage includes
the entire service area for which U.S. market access has already been granted.




A.3    FREQUENCY AND POLARIZATION PLAN


The relevant frequency plan is given in Table A.3-1, indicating channel center, polarization and
bandwidth. The table also shows the connectivity between each uplink and downlink band.

                                                2


Circular polarization is used on both the uplink and downlink with the downlink polarization being
orthogonal to the uplink polarization. The satellite re-uses the spectrum such that any channel is
re-used multiple times by a combination of polarization and spatial isolation. This satisfies the
requirements of §25.210(f) of the FCC’s Part 25 rules (the “Rules”).


                    Table A.3-1. Frequency Plan for U.S. Market Access
                                         Corresponding
 Uplink Center
                         Uplink         Downlink Center         Downlink              Bandwidth
  Frequency
                       Polarization       Frequency            Polarization             (MHz)
    (MHz)
                                            (MHz)
      28350           RHCP, LHCP             18550             LHCP, RHCP                500
      28850           RHCP, LHCP             19050             LHCP, RHCP                500
      29750           RHCP, LHCP             19950             LHCP, RHCP                500



As explained in section A.11, the 28.6-29.1 GHz and 18.8-19.3 GHz bands, or a portion thereof,
will cease to be used in the event that there is a need to protect an NGSO network.


A.4    MAXIMUM DOWNLINK EIRP AND EIRP DENSITY


The maximum operational downlink EIRP of all spot beams is 72.7 dBW. The maximum
operational downlink EIRP density varies by sub-band. The maximum operational downlink
EIRP density towards U.S. territory in the 18.3-18.8 GHz and 19.7-20.2 GHz bands varies
slightly depending on the spreading loss. ViaSat will not exceed a PFD on U.S. territory of -118
dBW/m2/MHz consistent with §25.138 (a)(6), which is the limit that is currently authorized for
VIASAT-2.     Because PFD is dependent on the slant path and hence spreading loss, the
maximum EIRP density from the satellite can vary accordingly. For example, for a spreading
loss of 162.1 dB, VIASAT-2 satellite transmissions would not exceed an EIRP density of 44.1
dBW/MHz.


The maximum operational downlink EIRP density towards U.S. territory in the 18.8-19.3 GHz
band will not exceed 40.9 dBW/MHz.




                                                 3


A.5      SATELLITE ANTENNA BEAMS AND ANTENNA GAIN CONTOURS


The satellite’s antenna gain contours are being provided to the Commission in a GIMS container
file.


The satellite’s payload employs multiple spot beams in both the uplink and downlink directions.
There are two types of spot beams: small beams (“A”-type beams) and larger beams (“B”-type
beams). For each beam-type, the beams are nominally identical.


ViaSat is providing the Commission with an isoline gain contour, in both uplink and downlink
directions, that depict, on a composite basis across the entire coverage area, the maximum gain
of all spot beams that may be operated within that area. In addition, the predicted antenna gain
contours for one transmit and receive representative spot beam for each of the two beam types,
and in both polarizations, is included in the associated GIMS file.


For on-station operations, the TT&C locations will be located in Albuquerque, New Mexico and
Des Moines, Iowa. In the associated GIMS file, the TT&C beams provided are identical to the
composite beams described above. On-station TT&C operations are conducted through the
communications spot beams.


For clarity, the following beams have been included in the associated GIMS file:


      1) RXAR and RXAL. These contain a composite beam contour, in both polarizations, for
         the uplink A-type beams.
      2) TXAR and TXAL. These contain a composite beam contour, in both polarizations, for
         the downlink A-type beams.
      3) RXBR and RXBL. These contain a composite beam contour, in both polarizations, for
         the uplink B-type beams.
      4) TXBR and TXBL. These contain a composite beam contour, in both polarizations, for
         the downlink B-type beams.
      5) CUR and TDR. These contain a composite beam contour, representing the uplink and
         downlink on-station TT&C beams, respectively.

                                                 4


      6) UPAT.    This contains a composite beam contour, representing the uplink autotrack
         beams.
      7) DNAT. The downlink beam used in support of the autotrack function.
      8) RXAR_REP and RXAL_REP. Representative spot beam contours for the uplink A-type
         beams, in both polarizations. Beam RXAR_REP also serves as the representative beam
         for command beam CUR.
      9) TXAR_REP and TXAL_REP. Representative spot beam contours for the downlink A-
         type beams, in both polarizations. Beam TXAR_REP also serves as the representative
         beam for telemetry beam TDR.
      10) RXBR_REP and RXBL_REP. Representative spot beam contours for the uplink B-type
         beams, in both polarizations.
      11) TXBR_REP and TXBL_REP. Representative spot beam contours for the downlink B-
         type beams, in both polarizations




The near-omni directional beams (beams OMNUR and OMNDR) used for on-station emergency
situations have gain contours that vary by less than 8 dB across the surface of the Earth, and
accordingly the gain at 8 dB below the peak falls beyond the edge of the Earth. Therefore,
pursuant to Section 25.114(vi)(A) of the Rules, contours for these beams are not required to be
provided and have not been included in the associated GIMS file.


A.6      TT&C CHARACTERISTICS


The information provided in this section complements that provided in the associated Schedule S
submission.


The TT&C sub-system provides for communications during pre-launch, transfer orbit and on-
station operations, as well as during spacecraft emergencies. When on-station, uplink beacon
transmissions are used to control pointing of the satellite’s antennas. The TT&C sub-system will
operate at the edges of the uplink and downlink frequency ranges during all phases of the
mission. All transmissions will operate in a circular polarization mode.


                                                5


During transfer orbit and on-station emergencies the TT&C subsystem employs a near-omni-
directional antenna configuration. During normal on-station operation, the telecommand
transmissions will be received via one of two uplink spot beams. A summary of the TT&C
subsystem’s characteristics is given in Table A.6-1.


               Table A.6-1. Summary of the TT&C Subsystem Characteristics
                                              Transfer Orbit and
                Parameter                                                   On-Station
                                                  Emergency
      Command/Ranging Frequencies and          29,501 MHz - RHCP         29,501 MHz - RHCP
                Polarizations                  29,999 MHz - RHCP         29,999 MHz - RHCP
      Minimum Command Flux Density                -82 dBW/m2                -117 dBW/m2
            Uplink Antenna Beam                       Near-Omni                 Spot
      Telemetry/Ranging Frequencies and        18,301 MHz - RHCP         18,301 MHz - RHCP
                Polarizations                  18,303 MHz - RHCP         18,303 MHz - RHCP
          Downlink Antenna Beam                       Near-Omni                 Spot
          Maximum Downlink EIRP                        7 dBW                  40 dBW




Additionally, an uplink autotrack beacon will be transmitted at a frequency of 29,501 MHz and
in RHCP, a downlink continuous wave (“CW”) signal is transmitted at 18,799.6 MHz in vertical
polarization in support of the autotrack function, as well as a 400 kHz pseudo-noise (“PN”)
modulated downlink carrier also transmitted at 18,799.6 MHz in vertical polarization. The CW
and PN carriers can be individually “extracted” on the ground, despite the fact that they transmit
on the same center frequency.


A.7     CESSATION OF EMISSIONS


Consistent with the originally authorized parameters for VIASAT-2, all downlink transmissions
can be turned on and off by ground telecommand, thereby causing cessation of emissions from
the satellite, as required by § 25.207 of the FCC’s rules.




                                                  6


A.8       POWER FLUX DENSITY AT THE EARTH’S SURFACE (18.3-19.3 GHZ BAND)


The maximum PFD emitted over U.S. territory by VIASAT-2 will remain compliant with the
§25.208(c) PFD limits that apply in the 18.3-18.8 GHz band. The PFD limits of §25.208(c) are as
follows:


      •   -115 dB(W/m2) in any 1 MHz band for angles of arrival between 0 and 5 degrees above the
          horizontal plane;
      •   -115+(δ-5)/2 dB(W/m2) in any 1 MHz band for angles of arrival δ (in degrees) between 5
          and 25 degrees above the horizontal plane; and
      •   -105 dB(W/m2) in any 1 MHz band for angles of arrival between 25 and 90 degrees above
          the horizontal plane.

In addition, §25.208(d) contains PFD limits that apply in the 18.6-18.8 GHz band produced by
emissions from a space station under assumed free-space propagation conditions as follows:


      •   -95 dB(W/m2) for all angles of arrival. This limit may be exceeded by up to 3 dB for no
          more than 5% of the time.

In the worst case, the PFD limits of §25.208(d) correspond to a PFD of -118 dBW/m2/MHz (i.e.,
-95-10*log(200)).


§25.208 does not contain any PFD limits that apply in the 18.8-19.3 GHz band for GSO satellite
networks, however it is noted that Article 21 of the ITU Radio Regulations does include PFD
limits applicable to GSO satellites using the 18.8-19.3 GHz band. The ITU limits are identical to
those in §25.208(c).


As explained in section A.9.1, ViaSat will operate the satellite such that downlink transmissions in
the 18.3-18.8 GHz band will not exceed a PFD level of -118 dBW/m2/MHz. This PFD level is in
compliance with both §25.208(c) and §25.208(d).


The maximum downlink EIRP density transmitted in the 18.8-19.3 GHz band will be 1.8 dB
lower than that transmitted in the 18.3-18.8 GHz band, therefore downlink transmissions in this
band also meet the applicable PFD limits.


                                                 7


A.9     TWO DEGREE COMPATIBILITY


The VIASAT-2 satellite network also remains compliant with the uplink off-axis EIRP density and
downlink PFD levels of §25.138, regardless of whether the frequency band used is subject to
§25.138.


A.9.1   Frequency Bands Subject to §25.138


For those frequency bands subject to §25.138, compliance with the Commission’s two-degree
spacing policy is ensured provided:


        1) The uplink off-axis EIRP density levels of §25.138(a)(1) of the Rules for blanket
             licensing are not exceeded;


        2) The maximum PFD levels of §25.138(a)(6) of the Rules for blanket licensing are not
             exceeded.


ViaSat will ensure that no authorized uplink transmissions towards the VIASAT-2 satellite will
exceed the clear sky uplink off-axis EIRP density limits of §25.138(a)(1). In cases where a
transmitting earth station does not meet the off-axis gain mask requirements of §25.209(a) and (b),
the maximum input power density into the antenna will be correspondingly reduced such that off-
axis EIRP density requirements of §25.138(a)(1) are still met.


In addition, ViaSat will ensure that no downlink transmissions in the 18.3-18.8 and 19.7-20.2
GHz bands from the VIASAT-2 satellite towards U.S. territory will exceed the -118
dBW/m2/MHz limit set forth in §25.138 (a)(6) of the Rules.


A.9.2      Frequency Bands Not Subject to §25.138


This section demonstrates that uplink transmissions in the 28.1-28.35 GHz and 28.6-29.1 GHz
bands and downlink transmissions in the 18.8-19.3 GHz band are two-degree compatible.




                                                 8


  Currently there are no operational GSO Ka-band satellites that use the 28.1-28.35 GHz, 28.6-29.1
  GHz and 18.8-19.3 GHz bands at or within two degrees of the 69.9º W.L. location, nor are there
  any pending applications before the Commission for use of these bands by a GSO satellite at or
  within two degrees of 69.9° W.L. Therefore, in order to demonstrate two-degree compatibility, the
  transmission parameters of the VIASAT-2 satellite have been assumed as both the wanted and
  victim transmissions.


  Table A.9-2 provides a summary of the uplink and downlink transmission parameters. These
  parameters were derived from the VIASAT-2 link budgets that are embedded in the Schedule S
  form and were used in the interference analysis. The interference calculations assumed a 1 dB
  advantage for topocentric-to-geocentric conversion and that all wanted and interfering carriers
  are co-polarized. The C/I calculations were performed on a per Hz basis.


  Table A.9-3 shows the results of the interference calculations in terms of the overall C/I margins.
  It can be seen that the C/I margins are positive in all cases.

  Table A.9-2. VIASAT-2 transmission parameters.
                                             Tx E/S    Uplink                          Rx E/S
                Emission Bandwidth                                Downlink EIRP                    C/I Criterion
Carrier ID                                    Gain      EIRP                            Gain
               Designator  (MHz)                                     (dBW)                             (dB)
                                              (dBi)    (dBW)                            (dBi)
    1          500MG7D         500             65.0     75.0            67.9             49.3          20.5
    2          500MG7D         500             65.0     75.0            67.9             40.7          13.8
    3          500MG7D         500             65.0     75.0            67.9             40.7           7.4
    4          500MG7D         500             65.0     75.0            67.9             33.7           9.3
    5          6M25G7D         6.25            44.3     48.8            48.9             61.4          16.4
    6          3M13G7D        3.125            44.3     48.8            45.9             61.4          15.1
    7          1M56G7D        1.563            44.3     48.8            42.9             61.4          10.1
    8          782KG7D       0.7813            44.3     46.6            39.9             61.4           8.9
    9          3M87G7D        3.874            37.3     39.9            46.8             61.4           9.3


                           Table A.9-3. Summary of the overall C/I margins (dB).
                                                        Interfering Carriers
              Carrier ID      1         2         3      4        5        6      7       8       9
                  1          8.3       8.3       8.3    8.3      6.3      5.0    3.1     2.5     2.4
                  2          6.5       6.5       6.5    6.5      6.1      5.8    5.2     5.0     5.0
   Carriers
   Wanted




                  3         12.8      12.8      12.8   12.8     12.5     12.2   11.6    11.4    11.3
                  4          4.0       4.0       4.0    4.0      3.9      3.8    3.7     3.6     3.6
                  5         19.4      19.4      19.4   19.4      7.3      4.4    1.4     0.5     0.4
                  6         22.6      22.6      22.6   22.6     11.6      8.7    5.7     4.9     4.8

                                                           9


            7        28.9    28.9    28.9    28.9     19.5    16.6    13.7    12.9    12.7
            8        30.4    30.4    30.4    30.4     21.5    18.6    15.7    14.9    14.8
            9        19.0    19.0    19.0    19.0      7.6     4.7     1.7     0.9     0.7




A.10      SHARING WITH LMDS AND WITH NGSO FSS IN THE 28.1-28.35 GHZ
       BAND


VIASAT-2 is authorized to operate in the United States using the 28.1-28.35 GHz band
designated for LMDS on a primary basis and for the FSS on a secondary basis. The
modifications to the satellite design do not impact the demonstration of compatibility provided in
ViaSat’s original letter of intent application. Applications for the earth station antennas
communicating with the VIASAT-2 and using the 28.1-28.35 GHz band within the U.S. will
include an appropriate demonstration that the proposed operations will not cause harmful
interference into any licensed LMDS station. The earth station licensee will take appropriate
actions to protect any future licensed LMDS station that has the potential to receive harmful
interference, including ceasing transmissions in the 28.1-28.35 GHz band if necessary.


O3b Limited (“O3b”) has received licenses from the Commission for gateway earth stations
located in Hawaii and Texas to communicate with O3b’s constellation of NGSO satellites using
the 28.1-28.35 GHz band on a secondary basis. 1 In addition, O3b has pending an application for
gateway earth station to be located in Virginia proposing to use the 28.1-28.35 GHz band on a
secondary basis. 2 The analysis in the following section, which demonstrates the compatibility of
VIASAT-2 operations in the United States with those O3b earth stations located in the U.S.
operating in the 28.6-29.1 GHz and 18.8-19.3 GHz bands, is equally applicable to operations in
the 28.1-28.35 GHz band. Currently no other operational NGSO systems are authorized by the
Commission to use the 28.1-28.35 GHz band, nor are there any other pending applications before
the Commission for use of the 28.1-28.35 GHz band by a NGSO system.




1
       See SES-LIC-20100723-00952 and SES-LIC-20130124-00089.
2
       See SES-LIC-20130618-00516 and SES-AMD-20131122-01187.
                                                 10


A.11    SHARING WITH NGSO FSS IN THE 28.6-29.1 GHZ AND 18.8-19.3 GHZ BANDS


VIASAT-2 is authorized to operate in the United States using the 28.6-29.1 GHz band
designated for NGSO FSS on a primary basis and for GSO FSS on a secondary basis. ViaSat’s
U.S. operations will be consistent with the obligations of a secondary user of spectrum to avoid
harmful interference into, and to accept any interference received from, primary users.


The highest interference levels that could occur into NGSO networks from the VIASAT-2
network are when there is an “in-line” event. On the uplink for example, an in-line event occurs
when the NGSO satellite, the GSO satellite and the interfering GSO earth station are all in a line.
As the NGSO satellite continues to move within its orbit, an angle between the NGSO satellite
and the GSO satellite, subtended at the GSO earth station, is created. As long as the GSO earth
station does not transmit when the NGSO satellite is within a certain angle, no harmful
interference to the NGSO satellite will occur. A similar situation exists on the downlink. The
amount of angular separation required will be dependent on the orbital and transmission
characteristics of the NGSO FSS networks, their earth station locations, and their interference
criteria.


O3b has received U.S. market access for its constellation of NGSO satellites.             O3b has
Commission authorization to use 28.6-29.1 GHz and 18.8-19.3 GHz bands to communicate with
gateway earth stations located in Hawaii and Texas as well as for earth stations on vessels
(“ESV”) operating within U.S. waters. 3 O3b also has a pending application for a gateway earth
station antenna (2.4 meter) to be located in Bristow, Virginia and has Commission authorization
to operate smaller antennas (1.2 and 2.2 meter) from Bristow, Virginia. 4 These smaller antennas
have identical transmission parameters as those of the ESV’s. In addition, O3b has a pending
application for a blanket license for the operation of fixed earth stations (1.2 meter, 1.8 meter,
2.2 meter and 2.4 meter) in CONUS, Hawaii, Puerto Rico and the U.S. Virgin Islands. 5 As was




3
    See SES-LIC-20100723-00952, SES-LIC-20130124-00089 and SES-LIC-20130528-00455.
4
    See SES-LIC-20130618-00516 and SES-AMD-20131025-01138.
5
    See SES-LIC-20141001-00781.

                                                11


the case with ViaSat’s original letter of intent application, the following analysis demonstrates
that no harmful interference between O3b’s system and the VIASAT-2 satellite network will
occur.


Currently no other NGSO networks are authorized by the Commission to use the 28.6-29.1 GHz
and 18.8-19.3 GHz bands. Northrop Grumman Space and Mission Systems Corp. (“Northrop
Grumman”) had previously received Commission authorization for its Global EHF Satellite
Network (“GESN”) and ATCONTACT Communications, LLC (“ATCONTACT”) had
previously received Commission authorization for its NGSO network. Both networks were to
utilize highly elliptical orbits (“HEO”). The interference analysis contained herein demonstrates
that the operations of the modified VIASAT-2 satellite network also would protect the HEO
satellite systems previously licensed to ATCONTACT and NGST from harmful interference.


A.11.1 Sharing with the O3b System


As described above, O3b has Commission authorization for operation of gateways in Hawaii and
Texas and for the operation of ESVs within U.S. coastal waters.             O3b also has pending
applications for operation of a gateway in Virginia and for operation of fixed earth station
terminals on a blanket basis in CONUS, Hawaii, Puerto Rico and the U.S. Virgin Islands.
ViaSat has examined each of these O3b scenarios and has found that the highest potential for
interference from the VIASAT-2 network into the O3b network would occur into O3b’s ESV
operations because these are the O3b ground antennas that can be located closest to the equator.
Due to its equatorial orbit, the closer to the equator that an O3b earth station is located, the more
interference it can receive from a GSO network. Similarly, the closer to the equator that a GSO
earth station is located, the more interference it can receive from the O3b network. The location
closest to the equator that is within U.S. territory, and visible to the VIASAT-2 satellite, is in
U.S. waters south of St. Croix, U.S. Virgin Islands (approximately 17.6°N, 64.75°W). The
following analysis assumes the VIASAT-2 and O3b networks each have an earth station
collocated at these geographic coordinates.


Table A.11-1 shows the pertinent transmission parameters of the VIASAT-2 network and the
O3b system.

                                                 12


                Table A.11-1. Summary of VIASAT-2 and O3b parameters.
                  Parameters                           VIASAT-2              O3b System
ESV Uplink Input Power Density                       -56.5 dBW/Hz           -53.4 dBW/Hz
Satellite Rx Antenna Gain                               53.6 dBi               34.5 dBi
Satellite Rx System Noise Temp                           1380 K                 1000 K
Satellite Tx EIRP Density                            -19.1 dBW/Hz          -28.32 dBW/Hz
Earth Station Rx System Noise Temperature                 224 K                  225 K



Table A.11-2 shows the interference calculations for the assumed worst case situation described
above. The results show that the O3b system is adequately protected. The calculated ΔT/T
values in all cases are small, indicating the technical compatibility of the VIASAT-2 satellite
network with the O3b network and with an O3b earth station located anywhere within U.S.
territory. ViaSat makes the following additional observations:


   1) In order to be conservative, the interference calculation of uplink interference into ViaSat
       uses an O3b uplink input power density of -53.4 dBW/Hz. This value is actually for an
       O3b gateway, not an ESV. The maximum power for an ESV is approximately 4 dB
       lower.


   2) In order to be conservative, the interference calculation of downlink interference into
       O3b uses a VIASAT-2 downlink EIRP density of -19.1 dBW/Hz.


   3) The interference analysis does not address the mutual interference environment with
       respect to O3b operations located outside of the U.S. For non-U.S. locations, ViaSat will
       operate in a manner consistent with Ofcom’s rules between U.K. registered satellite
       operators.




                                                13


                Table A.11-2. Interference calculations between VIASAT-2 and O3b.
Victim network                                                                        O3b      VIASAT-2
Interfering network                                                                 VIASAT-2     O3b

Uplink:
Frequency band                                                             GHz        28.85      28.85
Interfering uplink input power density                                   dBW/Hz       -56.5      -53.4
Angular separation between interfering E/S and victim satellite           degrees      9.9        9.9
Slant range (Interfering path)                                              km        8603      36165
Free space path loss (Interfering path)                                     dB        200.3      212.8
Atmospheric losses                                                          dB         1.2        1.2
Victim satellite receive antenna gain                                       dBi       34.5       53.6
Victim Satellite's Antenna Discrimination towards Interfering E/S           dB          0          0
Victim satellite Rx system noise temperature                                 K        1000       1380
No                                                                       dBW/Hz      -198.6     -197.2
Io                                                                       dBW/Hz      -219.4     -209.7
Io/No                                                                       dB        -20.8      -12.5
ΔT/T                                                                         %        0.82        5.6

Downlink:
Frequency band                                                             GHz        19.05      19.05
Interfering satellite downlink EIRP density                              dBW/Hz       -19.1     -28.32
Slant range (Interfering path)                                              dB       36165       8603
Free space path loss (Interfering path)                                     dB        209.2      196.7
Atmospheric losses                                                          dB          1          1
Angular separation between interfering satellite and victim E/S           degrees      9.9        9.9
Interfering Satellite's Antenna Discrimination towards Victim E/S           dB          0          0
Victim Rx earth station system noise temperature                            K          225        224
No                                                                       dBW/Hz      -205.1     -205.1
Io                                                                       dBW/Hz      -225.2     -222.0
Io/No                                                                       dB        -20.1      -16.9
ΔT/T                                                                        %         0.98        2.1




                                                                    14


A.11.2 Sharing with HEO Systems


This section analyzes compatibility of the modified VIASAT-2 satellite network with HEO
systems. Table A.11-3 summarizes the salient parameters of the VIASAT-2 network and the
GESN and ATCONTACT HEO satellite networks. The HEO network’s parameters are identical
to those used by Northrop Grumman and ATCONTACT to demonstrate independently that their
GSO operations in the 28.6-29.1 GHz and 18.8-19.3 GHz bands were compatible with the
other’s proposed NGSO operations. 6 The parameters of the two HEO networks are identical,
allowing a single interference analysis to be performed with respect to the VIASAT-89W
network.




      Table A.11-3. Summary of VIASAT-2 and GESN / ATCONTACT Parameters.

                Parameters                          VIASAT-2         GESN / ATCONTACT
                                                                           Systems
Minimum Operational Altitude                          GSO                 16000 km
Earth Station Uplink Input Power Density         -56.5 dBW/Hz          -63.45 dBW/Hz
Satellite Rx Antenna Gain                           61.0 dBi               46.5 dBi
Satellite Rx System Noise Temp                       1023 K                 504 K
Satellite Tx EIRP Density                        -19.1 dBW/Hz            -18 dBW/Hz
Earth Station Rx System Noise Temperature             224 K                 315 K


In order to demonstrate compatibility with these two NGSO networks, a worst case, static
interference analysis is performed.    The smallest possible angle will occur when the GSO
satellite, the NGSO satellite and the relevant earth station are all on the same longitude and the
earth station is at a high latitude. Assuming a minimum 10° elevation angle for the GSO earth
station, this sets the latitude to 71.4°N. The GESN and ATCONTACT satellites do not transmit
when they are at an altitude below 16000 km, which translates to a latitude of 31.9°N. With this
information, the smallest possible angular separation is then calculated to be 27.4 degrees. Both




6
    See SAT-AMD-20040719-00138 and SAT-AMD-20040719-00141.

                                               15


the transmitting GSO earth station (uplink calculation) and the victim NGSO earth station
(downlink calculation) have been assumed to be at a latitude of 71.4°N.


Table A.11-4 shows the results of interference calculations from the VIASAT-2 network into the
GESN and ATCONTACT networks and vice versa. The calculated ΔT/T values in all cases are
small, indicating the technical compatibility of the VIASAT-2 network with the GESN and
ATCONTACT networks.


The compatibility of these networks is largely due to the fact that the two NGSO networks do not
communicate with earth stations when their satellites cross the equatorial plane, thus in-line
events with a GSO network do not occur. For other types of NGSO constellations that do
communicate with earth stations when the satellites pass through the equatorial plane, it is
possible that an in-line interference event could occur. In order to protect such systems, ViaSat
will cease transmissions from the VIASAT-2 satellite and its associated earth stations such that
the required amount of angular separation with the NGSO network is always maintained.




                                               16


 Table A.11-4. Interference calculations between VIASAT-2 and GESN / ATCONTACT.

Victim network                                                GESN / ATCONTACT       VIASAT-2
Interfering network                                               VIASAT-2       GESN / ATCONTACT

Uplink:
Frequency band                                       GHz            28.85              28.85
Interfering uplink input power density             dBW/Hz           -56.5             -63.45
Angular separation                                  degrees         27.4               27.4
Slant range (Interfering path)                        km           21046              40586
Space loss (Interfering path)                         dB            208.1              213.8
Atmospheric losses                                    dB             1.2                1.2
Victim satellite receive antenna gain                 dBi           46.5                61
Victim satellite Rx system noise temperature           K             504               1023
No                                                 dBW/Hz          -201.6             -198.5
Io                                                 dBW/Hz          -223.3             -221.4
Io/No                                                 dB            -21.7              -22.9
ΔT/T                                                   %            0.680              0.512

Downlink:
Frequency band                                       GHz            19.05              19.05
Interfering satellite downlink EIRP density        dBW/Hz           -19.1               -18
Slant range (Interfering path)                        dB           40586              21046
Space loss (Interfering path)                         dB            210.2              204.5
Atmospheric losses                                    dB              1                  1
Angular separation                                  degrees         27.4               27.4
Victim Rx earth station system noise temperature      K              315                224
No                                                 dBW/Hz          -203.6             -205.1
Io                                                 dBW/Hz          -234.2             -227.4
Io/No                                                 dB            -30.6              -22.3
ΔT/T                                                  %             0.087              0.582

A.12     ORBITAL DEBRIS MITIGATION PLAN


A.12.1 Spacecraft Hardware Design


The VIASAT-2 satellite is based on the flight proven Boeing 702 HP heritage platform. The
following updated orbital debris mitigation plan takes into account the selected spacecraft bus.


ViaSat has assessed and limited the amount of debris released in a planned manner during
normal operations. The VIASAT-2 satellite has been designed so as to not become a source of
debris during launch, drift, or operating mode. All separation and deployment mechanisms, and
any other potential source of debris, are expected to be retained by the spacecraft or launch
vehicle.



                                                      17


In conjunction with the satellite manufacturer, ViaSat has assessed and limited the probability of
the satellite becoming a source of debris by collisions with small debris or meteoroids of less
than one centimeter in diameter that could cause loss of control and prevent post-mission
disposal. ViaSat and the satellite manufacturer have taken steps to limit the effects of such
collisions through shielding, the placement of components, and the use of redundant systems.


The VIASAT-2 satellite includes redundant TT&C, bus control electronics and propulsion
subsystems to ensure successful end-of-life disposal. The spacecraft TT&C system, vital for
orbit raising, will be extremely rugged with regard to meteoroids smaller than 1 cm, by virtue of
its redundancy, shielding, separation of components and physical characteristics. The TT&C
subsystem will have no single points of failure. Near-omni-directional antenna coverage is
provided through the use of a combination of independent bicone and forward/aft pipe antennas.
These antenna feeds are extremely rugged and capable of providing adequate coverage even if
struck, bent or otherwise damaged by a small or medium sized particle. The command receivers
and decoders and telemetry encoders and transmitters will be located within a shielded area and
will be totally redundant and physically separated. Two shielded xenon tanks and a redundant
pairs of thrusters provide the energy for orbit-raising.


A.12.2 Minimizing Accidental Explosions


In conjunction with the satellite manufacturer, ViaSat has assessed and limited the probability of
accidental explosions during and after completion of mission operations through a failure mode
verification analysis. The satellite manufacturer has taken steps to ensure that debris generation
will not result from the conversion of energy sources on board the satellite into energy that
fragments the satellite. All vessel pressures and battery cell voltages will be monitored by
telemetry. At end-of-life and once the satellite has been placed into its final disposal orbit,
ViaSat will remove all stored energy from the spacecraft by depleting any residual fuel, leaving
the liquid propellant latch valves open, venting the pressure vessels and leaving the batteries in a
permanent state of discharge. For xenon propellant, the latch valve is open if negligible xenon
remains. Otherwise, the xenon latch valves may remain closed.




                                                  18


A.12.3 Safe Flight Profiles


ViaSat has been granted authorization to locate the VIASAT-2 satellite at 69.9º W.L. and does
not seek to change this location in this application.


A.12.4 Post-Mission Disposal


There is no change to the originally planned post-mission disposal orbit altitude of 300 km above
the normal GSO operational orbit, which was based on the following analysis and calculation
under §25.283:


       Total Solar Pressure Area “A” = 128 m2
       “M” = Dry Mass of Satellite = 4197 kg
       “CR” = Solar Pressure Radiation Coefficient = 1.3


Therefore the Minimum Disposal Orbit Perigee Altitude:


               =       36,021 km + 1000 x CR x A/m
               =       36,021 km + 1000 x 1.3 x 128/4197
               =       36,061 km
               =       275 km above GSO (35,786 km)

To provide adequate margin, increasing the disposal orbit to 300 km will require 1.6 kg of xenon
propellant, taking account of all fuel measurement uncertainties, which will be allocated and
reserved in order to perform the final orbit raising maneuver.



A.13   WAIVER REQUEST


Section 25.210(i) of the Rules, 47 C.F.R. § 25.210(i), requires that space station antennas in the
FSS be designed to meet a cross-polarization isolation of 30 dB within the primary coverage area
of the antenna. The VIASAT-2 satellite’s transmit and receive antennas, including those used
for TT&C, can have a cross-polarization isolation as low as 24 dB. In support of its requested
waiver, ViaSat notes the following:
                                                 19


    1) The cross-polarization isolation shortfall creates a negligible amount of additional self-
        interference into the VIASAT-2 satellite network.                        All intra-system interference
        contributions, including the reduced cross-polarization isolation, have been taken into
        account in the design of the link budgets for the services that the satellite will provide.
        The link budgets are sufficiently robust to compensate for the negligible degradation
        caused by the reduced cross-polarization isolation performance.


    2) The uplink cross-polarization isolation shortfall is solely an intra-system design issue and
        has no effect on adjacent satellite networks.


        The downlink cross-polarization isolation shortfall creates a negligible amount of
        additional downlink interference into adjacent satellite networks. This is because the
        overall interference isolation of adjacent satellites is dominated by the receive earth
        station antenna off-axis discrimination for co-polar signals, and the contribution from the
        cross-polar component is negligible. A 24 dB cross-polarization isolation will decrease
        the downlink C/I into an adjacent satellite network by approximately 0.017 dB. In
        granting a similar waiver of Section 25.210(i), the Commission has determined that this
        level of increased interference is considered to be negligible. 7 Thus, grant of the
        requested waiver is consistent with prior Commission decisions granting similar waivers
        of Section 25.210(i), in which the Commission determined that cross-polarization
        performance of the downlink satellite antenna has only a second-order effect on the
        interference into the neighboring system. 8
                                     __________________________________




7
    See EchoStar Satellite Operating Corporation, DA 06-2590 ¶ 7 n.21 (rel. Dec. 22, 2006) (allowing a cross-
    polarization isolation of 22 dB, finding that cross-polar interference contribution representing a C/I decrease of
    0.03 dB is negligible).
8
    See id. ¶ 7.

                                                          20


             CERTIFICATION OF PERSON RESPONSIBLE FOR PREPARING
                         ENGINEERING INFORMATION




          I hereby certify that I am the technically qualified person responsible for preparation of

the engineering information contained in this pleading, that I am familiar with Part 25 of the

Commission’s rules, that I have either prepared or reviewed the engineering information

submitted in this pleading, and that it is complete and accurate to the best of my knowledge and

belief.




                                                                          /s/
                                                                ¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯
                                                                Stephen D. McNeil
                                                                Telecomm Strategies Canada, Inc.
                                                                Ottawa, Ontario, Canada
                                                                (613) 270-1177




                                                   21



Document Created: 2014-11-05 13:23:03
Document Modified: 2014-11-05 13:23:03

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